package model;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * model.User: 晓星航
 * Date: 2023-11-03
 * Time: 10:06
 */
//通过这个类，封装针对 博客表 的基本操作
public class BlogDao {
    //1.新增一个博客
    public void add(Blog blog) {
        Connection connection = null;
        PreparedStatement statement = null;
        try {
            //1.和数据库建立连接
            connection = DBUtil.getConnection();
            //2.构造SQL
            String sql = "insert into blog values(null, ?, ?, ?, ? )";
            statement = connection.prepareStatement(sql);
            statement.setString(1,blog.getTitle());
            statement.setString(2,blog.getContent());
            statement.setTimestamp(3,blog.getPostTimestamp());
            statement.setInt(4,blog.getUserId());
            //3.执行sql
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(connection, statement, null);
        }
    }
    //2.根据博客 id 来查询指定博客 (博客详情页中)
    public Blog selectById(int blogId) {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            //1.和数据库建立连接
            connection = DBUtil.getConnection();
            //2.构造sql语句
            String sql = "select * from blog where blogId = ?";
            statement = connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            //3.执行sql
            resultSet = statement.executeQuery();
            //4.遍历结果集和，由于blogId在blog表中是唯一的(主键)
            //此时的查询结果，要么是没有查到任何数据，要么只有一条记录！！！
            //此处可以不用while 使用if即可
            if (resultSet.next()) {
                Blog blog = new Blog();
                blog.setBlogId(resultSet.getInt("blogId"));
                blog.setTitle(resultSet.getString("title"));
                blog.setContent(resultSet.getString("content"));
                blog.setPostTime(resultSet.getTimestamp("postTime"));
                blog.setUserId(resultSet.getInt("userId"));
                return blog;
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            //5.释放必要的资源
            DBUtil.close(connection,statement,resultSet);
        }
        return null;
    }
    //3.直接查询出数据库中所有的博客列表(用于博客列表页)
    public List<Blog> selectAll() {
        List<Blog> blogs = new ArrayList<>();

        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
            try {
                //1.和服务器建立连接
                connection = DBUtil.getConnection();
                //2.构造 SQL 语句
                String sql = "select * from blog order by postTime desc";
                statement = connection.prepareStatement(sql);
                //3.执行sql
                resultSet = statement.executeQuery();
                //4.遍历结果集合
                while (resultSet.next()) {
                    Blog blog = new Blog();
                    blog.setBlogId(resultSet.getInt("blogId"));
                    blog.setTitle(resultSet.getString("title"));
                    //注意这里的正文！！！在博客列表页中，不需要把整个正文内容都显示出来！
                    String content = resultSet.getString("content");
                    if (content.length() >= 100) {
                        content = content.substring(0,100) + "...";
                    }
                    blog.setContent(content);
                    blog.setPostTime(resultSet.getTimestamp("postTime"));
                    blog.setUserId(resultSet.getInt("userId"));
                    blogs.add(blog);
                }

            } catch (SQLException throwables) {
                throwables.printStackTrace();
            } finally {
                DBUtil.close(connection,statement,resultSet);
            }
        return blogs;
    }
    //4.删除指定博客
    public void delete(int blogId) {
        Connection connection = null;
        PreparedStatement statement = null;
        try {
            //1.和数据库建立连接
            connection = DBUtil.getConnection();
            //2.构造 SQL 语句
            String sql = "delete from blog where blogId = ?";
            statement = connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            //3.执行 SQL
            statement.executeUpdate();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            //4.关闭
            DBUtil.close(connection,statement,null);
        }
    }
}
